1 88 BRITISH FRESH-WATER FISHES 



In habits and appearance the grilse, on returning from the 

 sea, is very similar to full-grown salmon, but persons accustomed 

 to deal with these fish can discriminate with certainty between 

 a 6 lb. salmon and a lo lb. grilse. The points of difference are 

 as difficult to define in writing as those which distinguish a girl 

 of sixteen from a woman of thirty. The grilse is smaller round 

 the tail than the salmon, as you will find if you try to lift it by 

 grasping it there ; the tail fin is more forked ; the snout is 

 sharper ; the general form of the fish is more elegant and the 

 scales more delicate in the grilse stage than in later periods 

 of growth. 



The salmon is what is termed an anadromous fish — that is, 

 one that " runs up " — and it is usually stated that the purpose 

 Habits of ^^^^^ which it ascends the rivers from the sea is that 

 the Salmon. Qf reproduction. No doubt that is one motive, for 

 salt water has been proved to be fatal to the vitality of the ova ; 

 but to represent it as the only, or even the principal, motive is 

 to misconstrue the facts of the life-history of the fish. In 

 certain rivers, such as the Tay, salmon run from the sea in 

 every month of the year ; in others, they begin to run 

 regularly in the spring months — February to May ; while in a 

 third class of river they put in no appearance whatever till late 

 in summer, or even in autumn. Now salmon appearing in 

 " late" rivers, or appearing in the autumn in what are known 

 as early rivers, do so in a more or less gravid condition, and 

 may be said to be leaving the sea for the purpose of depositing 

 their spawn ; but whereas the spawning season of salmon is 

 perfectly defined as extending from the middle of October, at 

 the earliest, to the end of January, how can it be said that fish 

 running in the first quarter of the year are doing so for the 

 purpose of spawning ? The question will be further considered 

 in the next chapter. 



Meanwhile, all that I wish to advance is that a portion, at 

 least, of the spring and early summer run of salmon return. 

 to the sea long before the regular spawning season ; it is clear 



